JPH0725546B2 - Solid acid substance and method for producing the same - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a ZrO ₂ -based solid acid substance, a method for producing the same, and a method for decomposing hydrocarbons using this solid acid substance.

TECHNICAL BACKGROUND OF THE INVENTION AND PROBLEMS OF THE INVENTION Attempts have been made for a long time to obtain industrially useful fractions having 3 to 4 carbon atoms in high yield from petroleum hydrocarbon compounds represented by naphtha. In this case, it is known that the solid acid catalyst is useful. Further, it is known that the solid acid catalyst is used for various reactions such as isomerization, alkylation and dealkylation of hydrocarbons. One of the properties that characterize such a solid acid is the acid strength of the solid acid, and a solid superacid having extremely strong acidity may be required depending on the reaction.

As such a solid superacid, conventionally, SbF_FiveSuch as metal
Fluoride is SiO₂-Al₂O₃Evaporated on metal oxide
(catalysttwenty one(4), 220, (1979)), ion exchange resin and AlC
l₃What reacted (J.Catalysis46, 266 (1977)), C
uSO_FourOr CuCl₂And AlCl₃A mixture of (catalysttwenty one
(4), 233 (1979), ZrO₂, Fe₂O₃Treated with sulfuric acid
Made (catalysttwenty two(4), 232, (1980)) etc. are known
ing.

These solid superacids are easily decomposed by contact with water, except for ZrO ₂ or SO ₄ ^2- , which is ZrO ₂ or Fe ₂ O ₃ treated with sulfuric acid, or Fe ₂ O ₃・ SO ₄ ^2-. However, there is a problem that it cannot be regenerated, and the temperature range in which it can be used as a catalyst is extremely narrow, so that it is difficult to apply it as an industrial catalyst.

The object of the present invention is to solve the problems associated with the prior art as described above, and it has extremely strong acid strength and easily decomposes super-strong acid points even when contacted with water. No
Moreover, it is an object of the present invention to provide a novel solid acid substance which can be used as a catalyst in a wide temperature range and is therefore expected to have a wide range of uses as an industrial catalyst.

Another object of the present invention is to provide a novel method for producing a solid acid substance as described above.

Still another object of the present invention is to provide a method for decomposing hydrocarbons using the above novel solid acid substance as a catalyst.

SUMMARY OF THE INVENTION A novel solid acid substance according to the present invention is ZrO ₂ · zF · mS [wherein z and m represent the weight% of F atom and the weight% of S atom with respect to the weight of ZrO ₂ , respectively, and z Is 0.1 to 10 and m is in the range of 0.01 to 5. ), The acid strength (Ho) has a strong acid point of -8.2 or less.

When this solid acid substance is measured by X-ray diffraction and X-ray photoelectron spectroscopy, it can be seen that it is a novel substance which is clearly different from ZrO ₂ .

The method for producing a metal oxide which is the novel solid acid according to the present invention is characterized by treating ZrO ₂ with SF ₆ at a temperature of 300 to 600 ° C.

Further, the method for decomposing hydrocarbons according to the present invention is a paraffin having 5 to 10 carbon atoms or a hydrocarbon containing the paraffin as a main component in the presence of the novel solid acid substance as described above. a)] is reacted to produce a lower aliphatic hydrocarbon (b) mainly containing paraffins having 3 to 4 carbon atoms.

The solid acid substance represented by the above formula ZrO ₂ · zF · mS obtained according to the present invention has extremely strong acid strength and does not easily decompose strong acid points even when it comes into contact with water, and can be used as a catalyst. Wide temperature range.

When the hydrocarbon (a) containing paraffins having 5 to 10 carbon atoms is reacted in the presence of the above solid acid substance, lower aliphatic hydrocarbons containing paraffins having 3 to 4 carbon atoms as a main component are obtained in high yield. To be

DETAILED DESCRIPTION OF THE INVENTION A novel solid acid substance according to the present invention, a method for producing the same, and a hydrocarbon decomposition reaction using the solid acid substance as a catalyst will be specifically described below.

Solid acid substance composition The novel solid acid substance according to the present invention is a ZrO ₂ -based metal oxide represented by ZrO ₂ · zF · mS and has an acid strength (Ho) of −8.2.
It has the following superacid points. In the above formula, z and m
Indicates the weight% of F atom and the weight% of S atom with respect to the weight of ZrO ₂ , respectively. And z is 0.1-10 and m is 0.0
It is in the range of 1-5. In the present specification, the ratio of F and S in the solid acid substance according to the present invention is shown as an average value of the whole solid acid substance. Since the solid acid substance of the present invention represented by ZrO ₂ · zF · mS is obtained by treating ZrO ₂ with SF ₆ as described below, the concentration of F and S on the surface of the solid is It is considered that the ratio is usually higher than the ratio of the range.

In the present invention, F and S in the solid acid substance according to the present invention are used.
Is measured by the oxygen flask combustion method.

Acid Strength (Ho) The new solid acid substance represented by the above formula has a strong acid point of acid strength (Ho) of −8.2 or less, but the acid strength (Ho) is measured by the catalyst 24 , (3). 241, (1982). Specifically, it is performed as follows. Sulfuryl chloride SO ₂ Cl ₂ 20cc granular blue silica gel 5g
And leave it for 1 day to dry the reagent. Take 3 cc of this dried sulfuryl chloride in a test tube and immediately add the catalyst to submerge it in the solution. A few drops of a 1% benzene solution of a Hammett indicator with a known pKa value is added to the solid acid substance, shaken lightly a few times and then allowed to stand to observe the color change of the catalyst surface. If the change is not clear, plug and leave for a few hours and wait. Commercially available 1,
When 3,5-trinitrobenzene (pKa value is -16.04) is used, the reagent usually contains a large amount of water, so after preparing a 1% benzene solution, add silica gel and leave it for several days to dry. To be used as an indicator.

Table 1 shows the relationship between the Hammett indicator used for measuring the acid strength (Ho) of the solid acid substance in the present invention and its pKa value. The procedure for measuring Ho using the indicator can be performed according to a known method. That is, an indicator with a large pK value and an indicator with a small pKa value are sequentially added to the sample, and the change in color of the sample is examined to determine the highest acid strength Ho of the sample.
Ask for. For example, 2,4-dinitrotoluene (pKa = -13.75) as an indicator changes its color to acidic, but 2,4-dinitrofluorobenzene (pKa = -14.52; basic color is colorless and acid is yellow). , I.e., for a sample that does not exhibit an acidic color, its Ho value is -14.52 <Ho <-13.
It is said to be in the range of 75. As is well known
Ho is approximately equal to the pKa value.

The above-mentioned acid strength (Ho) value is a value measured immediately after heating the solid acid substance in N ₂ at 400 to 600 ° C. immediately before measurement and then cooling to room temperature in a dry atmosphere.

In the ZrO ₂ · zF · mS solid acid substance according to the present invention, the acid strength (Ho) measured as described above is −8.2 or less.
Depending on the conditions for treating rO ₂ with SF ₆ , −13.75 <Ho <−1
It may have a super strong acid point of up to 2.70.

XRD analysis Such a solid acid substance represented by ZrO ₂ · zF · mS is analyzed by powder X-ray diffraction spectrum (XRD) to obtain ZrO ₂
Has a slightly different spectrum from.

The XRD diffraction pattern of ZrO ₂ · zF · mS according to the present invention
As shown in Figures (a), (b) and (c), the XRD of ZrO ₂ is also shown.
The diffraction pattern of is shown in FIG. Figure 1 (a) shows Zr
O ₂ was treated with SF ₆ at 350 ° C. for 30 minutes, FIG. 1 (b) was ZrO ₂ treated with SF ₆ at 400 ° C. for 10 minutes, and FIG. 1 (c) was ZrO ₂ Is treated with SF ₆ at 500 ° C. for 1 hour. The solid acid substance according to the invention shown in FIG.
Comparing ZrO ₂ with the XRD diffraction pattern, ZrO ₂ has a metastable tetragonal crystal structure, but when ZrO ₂ is treated with SF ₆ to form ZrO ₂・ zF ・ mS, it is a metastable tetragonal system. A monoclinic system peak appears from the system. This monoclinic peak becomes more apparent as the ZrO ₂ is treated with SF ₆ at a high temperature for a long time. However, the solid acid substance according to the present invention obtained by treating ZrO ₂ with SF ₆ shows that when ZrO ₂ is treated with SF ₆ for a long time at a high temperature such as 500 ° C. for 1 hour, the oxyfluorine content in the XRD increases. In some cases, the acid strength Ho is -8.2.
>Ho> -11.35, which does not have a very strong superacid point, while ZrO ₂ is treated at a relatively low temperature for a short time such as at 350 ° C. for 0.5 hour,
It has a super strong acid point such as −12.70>Ho> −13.75. Thus, the XR of the solid acid substance according to the present invention is treated as ZrO ₂ · mF · zS by treating ZrO ₂ at 350 ° C for 0.5 hours.
Regarding D analysis, this material still has a metastable tetragonal crystal structure, which is almost the same as ZrO ₂ , but the crystallization is slightly advanced compared to untreated ZrO ₂ .

The XRD analysis carried out in the present invention was carried out by preparing a powder sample in a dry nitrogen atmosphere under the following conditions and measuring it under the atmosphere.

Voltage: 40kv Current: 100mA Current Full: 800cps Time Constant: 0.5sec Scanning Speed: 4 ℃ / min Divergency: 1/2 ° Receiving Slit: 0.15mm X-ray: CuKα (1.54A) XPS analysis ZrO _{2 according to the} present invention The difference between zF · mS and untreated ZrO ₂ is also demonstrated by X-ray photoelectron spectroscopy (XPS). ZrO
The XPS analysis results before and after treating ₂ with SF ₆ are shown in Table 1 for 3d electrons of Zr, 1S electrons of F, and 1S electrons of O. From Table 1, in the solid acid substance according to the present invention, the spectrum of the 1s electron of the fluorine atom is detected, the 3d atom of Zr is shifted to about 0.4 eV high energy side, and the 1S electron of O is It can be seen that it is shifting to the high energy side by about 1 eV.

The ZrO ₂ · zF · mS used in this XPS analysis was obtained in Example 1 described later.

In the present invention, XPS analysis is carried out at room temperature using a sample of 35 to 80 mesh under a vacuum degree of about 1 × 10 ⁻⁶ Pa.
CIS was performed at 284.6 eV using MgKα or AlKα as the radiation source.

Method for Preparing Solid Acid Substance Next, a method for producing a solid acid substance represented by ZrO ₂ · zF · mS according to the present invention will be described.

The above solid acid substance according to the present invention can be obtained by treating ZrO ₂ obtained by a conventional method with SF ₆ at a temperature of 300 to 600 ° C., preferably 350 to 400 ° C.

ZrO ₂ is obtained, for example, by washing a hydroxide of zirconium obtained by hydrolyzing ZrO (NO ₃ ) ₂ .2H ₂ O with aqueous ammonia, washing with water, filtering and drying, and then calcining. In this case, the firing temperature of the dried product before SF ₆ treatment is usually 300 to 600 ° C, preferably 350 to 5
It is in the range of 00 ℃. Z instead of ZrO (NO ₃ ) ₂・ 2H ₂ O above
rOCl ₂ · 8H ₂ O may be used.

In the present invention, the method for obtaining ZrO ₂ to be subjected to the SF ₆ treatment is not limited to the above-mentioned method and may be prepared by any other commonly known method.

This ZrO ₂ has a temperature of 300-600 ° C, preferably 350-400 ° C.
It is treated with SF ₆ , but prior to the treatment with SF ₆ , ZrO ₂ is preferably heated and evacuated at a temperature equal to or higher than the above treatment temperature.

When treating ZrO ₂ with SF ₆ , if the treatment temperature is less than 300 ° C., it is not preferable because the resulting ZrO ₂ · zF · mS is less likely to have a super strong acid point, while if it exceeds 600 ° C., a similar result is obtained. ZrO ₂ · zF · mS is not preferable because it does not easily generate super strong acid points.

Hydrocarbon Decomposition Method Next, the hydrocarbon decomposition reaction using the solid acid substance represented by ZrO ₂ · zF · mS according to the present invention as a catalyst will be described.

The hydrocarbon decomposition reaction according to the present invention is performed by the above-mentioned ZrO ₂
・ In the presence of solid acid substance represented by zF ・ mS, carbon number is 5
~ 10 paraffins or hydrocarbons containing these paraffins as main components (these are called hydrocarbons (a)) are reacted to produce lower aliphatic hydrocarbons containing C 3 -C 4 paraffins as main components (these are It is characterized in that it produces hydrocarbon (b).

The hydrocarbon (a) used as a raw material in the catalytic reaction of the present invention is a paraffin having 5 to 10 carbon atoms or a hydrocarbon containing this paraffin as a main component. Such paraffins having 5 to 10 carbon atoms include n-pentane, 2-methylbutane, n-hexane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, n
-Heptane, 2-methylhexane, 3-methylhexane, 3-ethylpentane, 2,2-dimethylpentane, 2,3
-Dimethylpentane, 2,4-dimethylpentane, 2,2,3-
Specific examples thereof include trimethylbutane, n-octane, 3-ethylhexane, 2,5-dimethylhexane, nonane, and decane. Among these, n-hexane, 3-methylpentane, and 2,3-dimethylbutane are included. , N-heptane,
2-Methylhexane, 3-methylhexane, 3-ethylpentane, 2,2-dimethylpentane, 2,3-dimethylpentane and 2,4-dimethylpentane are preferably used.

In the present invention, not only can the paraffins be decomposed catalytically by mixing them alone or in combination of two or more, but also in addition to such paraffins, aromatic compounds such as cyclohexane, cyclohexene, benzene, decalin, tetralin, hexene and octene can be used. A hydrocarbon mixture containing other hydrocarbons such as a component, a naphthene component and an olefin component, and the content of paraffins having 5 to 10 carbon atoms is usually 30% by weight or more can also be used as a raw material.
Examples of such a hydrocarbon mixture raw material include light naphtha having a boiling point range of usually 30 to 130 ° C. obtained by distillation separation or contact separation of crude oil.

Such a reaction is usually carried out under the following conditions using a known vapor phase catalytic reactor.

The reaction is usually performed at a temperature in the range of 100 to 600 ° C, preferably 200 to 600 ° C. If the reaction temperature is lower than 100 ° C., a sufficient conversion cannot be obtained, which is not preferable. On the other hand, if the reaction temperature is higher than 600 ° C., the C ₁ and C ₂ fractions to be described later increase, which is not preferable.

In the present invention, the raw material hydrocarbon (a) is fed into the reactor through the preheater in a predetermined amount. In this case, the feed amount is room temperature and normal pressure, and when the raw material is a liquid, the feed amount is Is expressed as a liquid space velocity (LHSV), and this value is usually 0.01 to 10 hr ^-1 , preferably 0.1 to 5 h.
It is in the range of r ^-1 . When displayed in gas space velocity (GHSV), it is usually 10 to 10,000 hr ^-1 , preferably 100 to 1,0.
It is in the range of 00hr ^-1 .

Regarding the reaction pressure, it is usually carried out under atmospheric pressure, but if necessary, it may be carried out by appropriately increasing the pressure.
In the present invention, in carrying out the reaction, an appropriate amount of an inert gas such as nitrogen can be accompanied in the reactor if necessary.

After cooling the reaction product leaving the reactor, it is separated into a gas product and a liquid product, and then analyzed by gas chromatography.

When ZrO ₂ · zF · mS according to the present invention is used as a catalyst to react a hydrocarbon (a) having 5 to 10 carbon atoms, butane, pentane and propane are produced with high selectivity and are raw materials. The conversion rate of hydrocarbon (a) also shows an extremely high value.

The solid acid substance represented by the above formula ZrO ₂ · zF · mS obtained by the present invention has extremely strong acid strength and does not easily separate the super strong acid point even when contacted with water, and the catalyst As a wide temperature range can be used.

When the hydrocarbon (a) containing paraffins having 5 to 10 carbon atoms is reacted in the presence of the above solid acid substance, lower aliphatic hydrocarbons containing paraffins having 3 to 4 carbon atoms as a main component are obtained in high yield. To be

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

Example 1 500 g of ZrO (NO ₃ ) .2H ₂ O was dissolved in 3.5 l of distilled water, and aqueous ammonia was added to adjust the pH to 8-9. After stirring for 30 minutes at room temperature, the precipitate formed was washed thoroughly with water and filtered.
Zr (OH) ₄ was obtained. After drying this at 100 ℃ for 15 hours,
Classified to 80 mesh. This in air at 400 ℃, 3
ZrO ₂ was prepared by firing for hours.

This ZrO ₂ 2g was added to a quartz reaction tube (outer diameter about 2 cm, inner volume about 1
00cc) and evacuated at 400 ° C. for 1 hour. With the vacuum kept, the temperature was once cooled to room temperature, and SF ₆ was introduced until the pressure became normal pressure. Then heated to 350 ° C., for 30 minutes ZrO ₂ was contacted with SF ₆ at 350 ° C.. Further, vacuum evacuation was performed at 400 ° C. for 1 hour to obtain ZrO ₂ · zF · mS.

F and S in the obtained ZrO ₂ · F · S were measured, and the specific surface area was also measured. The results are shown in Table 2. The acid strength (Ho) of this substance was measured by the indicator method according to the method described in the specification, and the results are shown in Table 2.

Example 2 The same as Example 1 except that the treatment temperature, the treatment time, and the exhaust temperature of ZrO _{2 according to} the firing temperature SF ₆ were changed.

The results are shown in Table 3.

Example 3 Using the solid acid ZrO ₂ .zF.mS obtained in Example 1, a decomposition reaction of n-hexane was carried out as follows.

A pulse reactor directly connected to a gas chromatograph was used as a reactor, and 100 mg of a catalyst was charged in this pulse reactor, the reaction pressure was set to 1 kg / cm ² G, the reaction temperature was set to 200 ° C., and n-
Table 4 shows the results of the reaction performed by supplying 0.5 μl of hexane.
Shown in.

Analysis of reaction products and conversion of n-hexane were carried out by gas chromatography directly connected to a pulse reactor.

Example 4 Using the various solid acids obtained in Example 2, a decomposition reaction of n-hexane was carried out in the same manner as in Example 3.

The results are shown in Table 5.

Example 5 Prior to carrying out the decomposition reaction of n-hexane using the solid acid ZrO ₂ .zF.mS obtained in Example 1 as a catalyst,
0.5 μl of water was injected into the catalyst charged in the pulse reactor at 10 ° C. for 10 pulses at 600 ° C. to bring the catalyst into contact with steam, and then the reaction was performed using the catalyst heated at a temperature of 400 ° C. for 30 minutes. The results are shown in Table 6.

It can be seen from Table 6 that the activity of the solid acid substance of the present invention as a catalyst hardly changes even when it comes into contact with water.

[Brief description of drawings]

1 (a), (b) and (c) are powder X-ray diffraction spectra of ZrO ₂ .zF.mS, and FIG. ₂ are powder X-ray diffraction spectra of ZrO ₂ .

Claims (2)

[Claims] 1. The formula ZrO ₂ .zF.mS ... [I] [In the formula, z and m respectively represent the weight% of F atom and the weight% of S atom with respect to the weight of ZrO ₂ . And z is 0.1
~ 10 and m is in the range of 0.01-5. ],
Characterized in that the acid strength (H ₀₎ has a -8.2 following strong acid sites, ZrO ₂ based solid acid material. 2. ZrO ₂ having a strong acid point represented by the following formula [I] and having an acid strength (H ₀ ) of −8.2 or less, characterized by treating ZrO ₂ with SF ₆ at a temperature of 300 to 600 ° C. Method for producing _2- based solid acid substance: Formula ZrO ₂ · zF · mS ... [I] [In the formula, z and m respectively represent the weight% of F atom and the weight% of S atom relative to the weight of ZrO ₂ . And z is 0.1
~ 10 and m is in the range of 0.01-5. ]